In recent years, a great demand has emerged for the production of low-cost and high-performance antennas in the microwave and millimeter-wave range, especially for telecommunications, radar and monitoring applications. Planar solutions, employing parallel-plate-based RF transmission-line systems, have been proposed and are considered to be the most advantageous in terms of frequency bandwidth performance, cost, RF insertion loss, and overall compactness.
A problem with open microwave structures with large mechanically-unsupported RF-active regions, such as parallel-plate structures, is their susceptibility to mechanical shock, vibration, and/or deformation, which undesirably alters the RF properties of the structure (resonant frequency, propagation speed, field uniformity, etc.) In the special case of antenna structures employing parallel-plate transmission lines realized as large open regions, undesired deformation in the spacing and/or shape of the parallel-plate surfaces creates detrimental impacts on antenna pattern gain and sidelobe properties.